package com.hducms.common.util;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class AES {  
 
    public static String encrypt(String seed, String cleartext) throws Exception {    
        byte[] rawKey = getRawKey(seed.getBytes());    
        byte[] result = encrypt(rawKey, cleartext.getBytes());    
        //return toHex(result);
        return Base64.encode(result);
    }    
        
 
    public static String decrypt(String seed, String encrypted) throws Exception {    
    	@SuppressWarnings("static-access")
		byte[] enc=new Base64().decode(encrypted);
        byte[] rawKey = getRawKey(seed.getBytes());    
       // byte[] enc = toByte(encrypted);    
        byte[] result = decrypt(rawKey, enc);    
        return new String(result);    
    }    
   
    private static byte[] getRawKey(byte[] seed) throws Exception {    
        KeyGenerator kgen = KeyGenerator.getInstance("AES");    
        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");    
        sr.setSeed(seed);    
        kgen.init(128, sr); // 192 and 256 bits may not be available    
        SecretKey skey = kgen.generateKey();    
        byte[] raw = skey.getEncoded();    
        return raw;    
    }    
   
        
    private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {    
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");    
        Cipher cipher = Cipher.getInstance("AES");    
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);    
        byte[] encrypted = cipher.doFinal(clear);    
        return encrypted;    
    }    
   
    private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {    
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");    
        Cipher cipher = Cipher.getInstance("AES");    
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);    
        byte[] decrypted = cipher.doFinal(encrypted);    
        return decrypted;    
    }    
   
    public static String toHex(String txt) {    
        return toHex(txt.getBytes());    
    }    
    public static String fromHex(String hex) {    
        return new String(toByte(hex));    
    }    
        
    public static byte[] toByte(String hexString) {    
        int len = hexString.length()/2;
        byte[] result = new byte[len];
        for (int i = 0; i < len; i++)
            result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();
        return result;
    }    
   
    public static String toHex(byte[] buf) {    
        if (buf == null)    
            return "";    
        StringBuffer result = new StringBuffer(2*buf.length);    
        for (int i = 0; i < buf.length; i++) {    
            appendHex(result, buf[i]);    
        }    
        return result.toString();    
    }    
    private final static String HEX = "0123456789ABCDEF";    
    private static void appendHex(StringBuffer sb, byte b) {    
        sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));    
    }    
    
    public static void main(String[] args) {
		String key="123";
		String m ="23456789";
		String c = null;
		try {
			c=encrypt(key, m);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		System.out.println(c);
		String m1=null;
		try {
			m1=decrypt(key, c);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		System.out.println(m1);
	}
}  